﻿using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace WP7iPhone
{
    /// <summary>
    /// Mediator that forwards Offset property changes on to a ScrollViewer
    /// instance to enable the animation of Horizontal/VerticalOffset.
    /// 
    /// This code based on David Anson's blog entry:
    /// http://blogs.msdn.com/b/delay/archive/2009/08/04/scrolling-so-smooth-like-the-butter-on-a-muffin-how-to-animate-the-horizontal-verticaloffset-properties-of-a-scrollviewer.aspx
    /// 
    /// I just hacked on it to make it work for HorizontalOffset and took out the multiplier since I didn't need that
    /// </summary>
    public class ScrollViewerOffsetMediator : FrameworkElement
    {
        /// <summary>
        /// ScrollViewer instance to forward Offset changes on to.
        /// </summary>
        public ScrollViewer ScrollViewer
        {
            get { return (ScrollViewer)GetValue(ScrollViewerProperty); }
            set { SetValue(ScrollViewerProperty, value); }
        }
        public static readonly DependencyProperty ScrollViewerProperty =
            DependencyProperty.Register(
                "ScrollViewer",
                typeof(ScrollViewer),
                typeof(ScrollViewerOffsetMediator),
                new PropertyMetadata(OnScrollViewerChanged));
        private static void OnScrollViewerChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            var mediator = (ScrollViewerOffsetMediator)o;
            var scrollViewer = (ScrollViewer)(e.NewValue);
            if (null != scrollViewer)
            {
                scrollViewer.ScrollToHorizontalOffset(mediator.HorizontalOffset);
            }
        }

        /// <summary>
        /// HorizontalOffset property to forward to the ScrollViewer.
        /// </summary>
        public double HorizontalOffset
        {
            get { return (double)GetValue(HorizontalOffsetProperty); }
            set { SetValue(HorizontalOffsetProperty, value); }
        }
        public static readonly DependencyProperty HorizontalOffsetProperty =
            DependencyProperty.Register(
                "HorizontalOffset",
                typeof(double),
                typeof(ScrollViewerOffsetMediator),
                new PropertyMetadata(OnHorizontalOffsetChanged));
        public static void OnHorizontalOffsetChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            var mediator = (ScrollViewerOffsetMediator)o;
            if (null != mediator.ScrollViewer)
            {
                mediator.ScrollViewer.ScrollToHorizontalOffset((double)(e.NewValue));
            }
        }
    }
}
